When scientists talk about the cryosphere, they mean the places on Earth where water is in its solid form, frozen into ice or snow. Read more ...

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Summary

This data set consists of surface-based radar measurements, including geometry of the bed, surface, and internal layers, and bed reflectivity measurements at two sites along ice stream margins at Siple Dome, Antarctica. The research is a radar examination of bed reflection characteristics and internal layer geometry in two inter-ice-stream ridges, the Shabtaie Ridge (Ridge D/E) and the Engelhardt Ridge (Ridge B/C), and across margins with the adjacent ice streams, the MacAyeal Ice Stream (Ice Stream E) and the Whillans Ice Stream (Ice Stream B). Investigators collected these radar data from 14 November through 13 December 1998.

Data are in Microsoft Word, PDF, ASCII text, MATLAB, binary, and various image formats. Investigators have also provided code for MATLAB routines that they used to view the radar data. Data are available via FTP.

Parameter or Variable

Quality Assessment

Because the airwave signal swamps the first 1 µs of the data record, the first step in data processing is to remove the mean waveform from the profile to remove the airwave effect and reveal shallow layer information in the first 1 µs. Since the GPS data have not been fully processed, absolute error in vertical elevation could be as large as 50 m, so the displayed elevation scales for the radar profiles should be considered approximate. The profiles displayed in images are based on data files that have been subjected to demeaning and filtering and would therefore not be appropriate for any analyses directed toward accurate assessment of amplitude and phase without careful consideration.

3. Data Access and Tools

Data Access

Volume

The entire data set is 519 MB.

Software and Tools

MATLAB, IDL, ENVI, XV, Ghostview, and ImageMagick are some of the possible tools for viewing the radar data. Investigators have provided the codes used to view the data in MATLAB. Visit GPR IDL Tools for more information on viewing radar data with IDL software tools.

Visit MALA GeoScience, which is the manufacturer of the radar system that the investigators used, for information on additional software available for viewing the radar data.

4. Data Acquisition and Processing

Instrument Description and Acquisition Methods

This data set includes radar profiles from within the ice and its base and surface elevation profiles. Investigators collected radar data every 5 meters for profiles across the ice stream shear margins and approximately every 20 meters for profiles on the inter-ice stream ridges using 2 MHz antennae. The recording system was centered on a Tektonix TDS410 digital oscilloscope. Investigators used Garmin GPS100 SRVYII receivers to report differential GPS data.

Derivation Techniques and Algorithms

An overview of the methods that the investigators used to collect and reduce the data is available on the University of Washington's Glaciology Group Web site, http://www.geophys.washington.edu/Surface/Glaciology/PROJECTS/radar/. A copy of this documentation, RESDataAnalysisHowTo.pdf, is provided with the data in the METHODS directory. Routines for converting the raw binary data from the recording system to MATLAB-readable files and other miscellaneous MATLAB scripts are provided in the CODE subdirectory of the METHODS directory.

Processing Steps

Detailed processing information can be found in the investigator-provided documentation, datareport.pdf, that is included with the data.